T-Rex, Merciless Killer or Garbage Disposal Unit?

Reuters ^ | Thu, Jul 31, 2003 | Jeremy Lovell

[presidio9]

For a century, the towering Tyrannosaurus Rex has been regarded as a savage killer marauding unchallenged across the later dinosaur era.

But a new exhibition at London's Natural History Museum asks whether the monster meat-eater was instead a lumbering bully which lived on rotting corpses or used its bulk to rob smaller dinosaurs of their prey.

"I believe it was a scavenger pure and simple because I can't find any evidence to support the theory that it was a predator," paleontologist Jack Horner said at the opening on Thursday of "T-Rex -- the killer question."

Horner, the inspiration for scientist Alan Grant -- played by Sam Neill -- in Steven Spielberg's "Jurassic Park," said the lumbering giant was too slow, its arms too small and its sight too poor to catch anything moving.

On the other hand -- like a vulture -- the part of its brain dedicated to smell was huge and its giant jaws were bone crushers not flesh cutters.

"Everything says this dinosaur lived on dead meat. Even statistically we find that plant-eating dinosaurs were far more common than predators, and T-Rex is the second most common dinosaur," said Horner from Montana's Museum of the Rockies.

Although Natural History Museum paleontologist Angela Milner agreed that T-Rex was not built to run far or fast, she said there was nothing to suggest it could not catch and kill slow moving prey -- although falling over might be a problem.

"Research in the United States suggests that falling over while running might have been fatal because of its bulk. But I think it was partly a scavenger and partly a hunter. I believe it could have killed old or weak animals," she said.

Visitors to the exhibition which includes life-sized animated models of the 16-foot tall, six-ton brute attacking and eating its four-legged meals will get the chance to make up their own minds over the next nine months.

But a show of hands by the group of children at the opening on Thursday already suggested the likely answer -- almost all said T-Rex was probably a combination predator-scavenger.

"The answer is that we will probably never be certain, but as long as we keep asking the questions we are serving science," said an unfazed Horner.

[Sir Gawain]

the part of its brain dedicated to smell was huge

How can they possibly know this?

[mewzilla]

With those teeny li'l forearms, my money's on scavenger.

[Huck]

I like to think of T Rex as a giant crow or buzzard. Total comedown. But I seriously get the impression most of these paleo science guys make it up as they go. Ever watch the dino shows on Discovery? Big pile of fiction.

[Right Wing Professor]

Big, scary, extinct garbage truck Science forum ping.

[egarvue]

If I recall correctly, Jack Horner is a rather controversial figure in paleontology. He's the main proponent of "birds as dinosaurs" theory. I'll wait on the opinions of a few more solid palentologists before I'll jump on the Jack Horner bandwagon.

[Arrowhead1952]

Sofisticated wild a$$ guess (SWAG)

[ko_kyi]

Another thing - since predators are usually pretty fast, that thing would have had to eat ridiculous amounts of food. Are there any non-sea predators anywhere close to that size?

Scavenger makes a lot more sense. It is big enough to shoo away actual predators from their kills.

[mewzilla]

Well, fast is relative. Cheetahs are fast, but they're built for sprinting not long endurance runs. TR had really great thighs, so maybe he could sprint and bring down something that couldn't put up much of a fight. And as far as size goes, I think the carnosaurs were all over the place, weren't they? From the little nano-tyrano deals up to the really big guys? Probably affected how much they caught rather than how they caught it. I guess. I haven't kept up.

[ClearCase_guy]

If I recall correctly, Jack Horner is a rather controversial figure in paleontology. He's the main proponent of "birds as dinosaurs" theory.

What this fellow seems to do, is sit in a corner and pluck wild ideas out of the air -- sometimes he has a plum idea, but he is mostly all thumbs.

[Gorjus]

With those teeny li'l forearms, my money's on scavenger.

Um, and that logic applies to boa constrictors how? (*smile*)

Actually, I agree it was likely to be a scavenger, but I saw an interesting show on Discover (or something) that offered an interim condition. Carnosaur teeth were so full of rotting meat (didn't brush or floss, y'know) that they were really likely to cause a serious infection with even a single bite.

So, here's a scenario. T-Rex comes upon a herd of very slow-moving sauropods (using their smell to find them if nothing else) and snaps at one of them. If he connects (happens reasonably often, even if he can't see well enough to bite at specific vulnerable areas and achieve a quick kill), the sauropod gets infected with whatever was growing in the T-Rex's teeth and dies. T-Rex (one or another of them) finds the carcass and feeds on that.

What I like best about that sort of image is that it's not a simple either/or model, and life is usually full of strange combinations of things.

[Mike Darancette]

I would imagine that a large eating machine like T-Rex was opportunistic. If it was already dead - cool, almost dead T-Rex would help it along and on top of that T-Rex was an ambush hunter.

In those days meat was meat. Nothing could be too proud.

[mewzilla]

Works for me. And I really appreciate your point about simple models. I mean, how are they going to classify Mr. T? A certain percentage of kills makes him predator vs. a scavenger? If so they're going to have a problem since he's not around to ask :)

[presidio9]

Another thing - since predators are usually pretty fast, that thing would have had to eat ridiculous amounts of food. Are there any non-sea predators anywhere close to that size?

As someone pointed out, fast is relative. Also, predator-prey relationship are relative. There are no prey animals today the size of dinosaurs, but the largest land carnivore today, the polar bear, is plenty large relative to the seals it hunts.

[Gorjus]

. . the part of its brain dedicated to smell was huge

How can they possibly know this?

Know, as in absolute certainty? I'd say they can't. However, all vertebrate brains are arranged pretty much the same way. Corresponding areas of the brain, from the frontal lobes to the brain stem, control the same sort of things. There are distinct areas that govern sight, smell, hearing, touch, etc.

The relative size of the various parts of the brain, which can be determined with some accuracy by looking at the brain cavity in fossilized skulls, gives a pretty good idea on how well a particular capability was developed.

That's what the statement is - that the part of the brain dedicated to smell was huge - but there is usually corroborating evidence as well. Large nostrils with extensive tissue to absorb smells versus small eyes with a poor resolution capability, for example, can confirm the evidence of the brain cavity itself, and all those are determinable from fossilized remains.

As the saying goes, "The race is not always to the swift, nor the victory to the strong - but that's the way to bet."

[CaptRon]

Is it him or is it the guy with the straw hat and the scraggly beard? Can't think of his name.

[trebb]

the part of its brain dedicated to smell was huge

How can they possibly know this?

Perhaps they're DimocRATs and they want it to be that way. No better way to make it so than to say it like you believe it...

[Junior]

How can they possibly know this?

The brain leaves a cast inside the skull (or, more accurately, the skull fits around the brain like a glove to protect it). The shape of the brain can be determined from this. Dinosaur brains have parts corresponding to parts found in modern critters, and the part in the T. Rex brain corresponding to scent processing is fairly large.

[Junior]

What this fellow seems to do, is sit in a corner and pluck wild ideas out of the air -- sometimes he has a plum idea, but he is mostly all thumbs.

Do you have any clue as to what paleontologists do? Or, if it's something you don't understand you just claim it to be some sort of crap shoot?

[katana]

That's exactly how Komodo Dragons kill their prey (bite - infect - wait for it to die - lunch!) so your point is excellent.